Buying property, preferably once it's fallen into disarray so that it can be acquired at a discount. Develop the property with Black developers and black urban planners. Only provide services to Black home seekers and black business owners. Build up the community financially so that everything that has been touched, built, developed or re-developed is done so with black dollars. Then petition with the districts/municipalities to un-incorporate that area from the city limits.
Now, before anyone says anything, it might seem counter productive because being incorporated within a city's district or municipality or whatever guarantees, services like Emergency Services(Police, Fire, Ambulance, etc), but with the money the community would be raking in as a group, and how the money would(and should) be distributed throughout the community, we SHOULD be able to comfortably foot the bill ON OUR OWN so that we aren't at the mercy of a white supremacist system like the one we're currently living in.
I know it sounds lofty but, I think it would do a world of good in the long term.
Controlling the money.
That needs to be the ultimate goal to not only fix, but prevent problems in our communities.